The main objective of the proposed research is to measure and to correlate the integrated concentrations and production rate of various peptides, catecholamines and steroid hormones (hGH, insulin, glucagon, cortisol, 17-hydroxyprogesterone...etc.) in some physiological and pathological conditions. The integrated concentration of the hormone under consideration is measured in a pool of blood withdrawn at a constant rate utilizing a small portable pump connected to a heparinized catheter developed by the investigators. In addition, continuous monitoring of blood glucose is carried out by connecting the nonthrombogenic system to a glucose analyzer.